Assessing the potential of Salix alaxensis for the rhizoremediation of diesel contaminated soil

Abstract

Alaska has over 280 remote communities that rely on diesel as their main source of heat; as a result, there have been multiple diesel spills across the state. Research has shown that plants are able to assist in the degradation of diesel through rhizoremediation, relying on the interaction between microorganisms, plant roots, and other components of the soil environment. Greater attention is now being given to the potential role of secondary plant compounds released during fine root turnover and the stimulatory effects they may have on the rhizoremediation process. For this study the native plant species, Salix alaxensis (felt leaf willow) was chosen. Fine root turnover in the sub-Arctic was mimicked through a microcosm study performed with sub-Arctic soil contaminated with weathered and fresh diesel, incubated at 4 °C and 20 °C. The effect of adding crushed willow roots was compared against addition of pure salicylic acid, a secondary plant compound found in the salicaceae family, and/or addition of fertilizer. Results showed that the addition of crushed fine willow roots with or without fertilizer increased diesel loss. Overall, greater loss and higher respiration occurred at 20 °C. The addition of salicylic acid with or without fertilizer increased soil toxicity. Toxicity may have been the result of observed phenol production and/or fungal growth. Findings show promise for the use of Salix alaxensis for the rhizoremediation of diesel contaminated soils in the sub-Arctic.